For many millennia, humans have used biomass for three broad purposes: food for humans and fodder for farm animals; energy; and materials. Food has always been exclusively produced from biomass, and in the year 1800, biomass still accounted for about 95% of all energy. Biomass has also been a major source of materials for construction, implements, clothing, bedding and other uses, but some researchers think that total human uses of biomass will soon reach limits of sustainability. It is thus important to select those biomass uses that will maximise global climate change benefits. With a ‘food first’ policy, it is increasingly recognised that projections of food needs are important for estimating future global bioenergy potential, and that non-food uses of biomass can be increased by both food crop yield improvements and dietary changes. However, few researchers have explicitly included future biomaterials production as a factor in bioenergy potential. Although biomaterials’ share of the materials market has roughly halved over the past quarter-century, we show that per tonne of biomass, biomaterials will usually allow greater greenhouse gas reductions than directly using biomass for bioenergy. particularly since in many cases, biomaterials can be later burnt for energy after their useful life.